Numbers 4:41-43

New Catholic Bible

⁴¹ This was the number of the families of the sons of Gershon, all of whom served in the tent of meeting, whom Moses and Aaron counted, fulfilling the commandment of the Lord.

⁴² The Merarites were counted by families and clan, ⁴³ those who were from thirty years old to fifty years old and who went in to minister in the service of the tent of meeting.